Corn Is Ready, Soybeans Are Facing New Pests

LAMAR, MO.
   Corn fields east of Lamar and in the Milford and Nashville areas are fully mature and many are ready for harvest based on a scouting report done Aug. 31.
   “Many fields showed numerous blank ears due to dry weather this season. Others had ears with some tipping back of the kernels,” said Tim Schnakenberg, the agronomy specialist with University of Missouri Extension who scouted the fields.
   Yield reports show very marginal yields and low test weights in corn. According to Schnakenberg, there continues to be concern for aflatoxin in the grain, but most loads have been within the tolerance levels.
   “That could change if moisture comes back into the forecast,” said Schnakenberg.
   Soybeans scouted this week were in R4 and R5 full pod and beginning seed stages of development. Dry weather continues to be the biggest concern to fill pods for the remainder of the season.
   “There have been some cases of potash deficiency resulting in leaf yellowing and stunting. This is worsened in a dry year,” said Schnakenberg.
   The most obvious pests on soybeans currently are soybean podworms and green cloverworms. The larvae will feed on the foliage and the podworms especially cause pod damage.
   For podworm, the economic threshold at this stage of development is 20 percent defoliation or when larval numbers exceed one per foot of row and 5 percent or more of the pods are damaged.
   For green cloverworm the threshold is 20 percent defoliation and when 10-15 or more half grown or larger larvae are present per foot of row.
   “Current market prices and yield potential of the crop must be a consideration for making decisions on spraying,” said Schnakenberg. Δ
 




 Leaf Feeding














Podworm Feeding











Potash Deficiency
Photos by Tim Schnakenberg, Agronomy Specialist with University of Missouri Extension.